Three months after launch, Pinterest brings Bigcommerce, Magento and IBM Commerce on board, says the number of Buyable Pins has doubled to 60 million.

The company announced today that is it partnering with three more e-commerce platforms — Bigcommerce, Magento and IBM Commerce — to offer merchants access to sell directly on Pinterest. Pinterest also has switched the feature on for Bloomingdale’s, Wayfair, DVF, Steven Alan and thousands of new merchants from Shopify and Demandware, the e-commerce platforms it launched with.

When Pinterest launched the feature in June, it said 30 million Pins included the blue “Buy it” button that enables people to make purchases with a few taps on an iOS device. Today, the company says total Buyable Pins have doubled to 60 million. Pinterest isn’t taking a cut of transactions; it plans to make money by offering merchants the ability to promote Buyable Pins, though it isn’t doing that yet.

Pinterest isn’t sharing many details about how the pins are performing but is obviously bullish about their potential as the holiday retail season heats up. Shopify merchants are seeing mobile conversion rates two times higher than other Pins, Pinterest head of commerce Michael Yamartino wrote in a blog post. The post also said that two Shopify clients, online clothing boutique Spool No. 72 and handmade goods provider Madesmith, each are seeing that Buyable Pins are being used mostly by new customers. And as we reported last month, Madesmith says more than seven percent of its total sales from July to September have come from Buyable Pin purchases.

Yamartino added:

We’re also seeing that Pinners are open to buying products at different price points from their mobile devices. Whether it’s Freyrs sunglasses, a hammock chair or a pair of stylish Neiman Marcus boots, people are checking out with businesses of all sizes.

This supports recent research from Millward Brown, which found that 93 percent of Pinners use Pinterest to plan purchases and 87 percent of Pinners have purchased something because of Pinterest. Buyable Pins makes it seamless to go from planning to purchase.

Pinterest, of course, isn’t the only platform making a strong push into commerce. Last week, Twitter announced integrations with its buy button with some of the same e-commerce platforms — Shopify, Demandware and Bigcommerce. “We have gone from testing this with hundreds of merchants to millions of merchants,” Twitter head of commerce Nathan Hubbard told the New York Times. Facebook is still experimenting with a buy button — also via a Shopify integration — but COO Sheryl Sandberg said last week at Ad Week in New York that the social network isn’t ready to make the effort a priority.

Clearly, Pinterest feels differently, fittingly because it is trying to position itself as something other than a social network. People on Pinterest are planning for things they want to do or buy; Buyable Pins, long the No. 1 requested feature by Pinterest users, simplify that process.

“The goal is not for us to become Amazon,” Pinterest CEO Ben Silbermann said on stage at IAB Mixx in New York last week. “We’re not trying to be a commerce service, but we want to be this planning tool for the future, and if you want to buy those things, we want to make it very easy.”